Chronic kidney disease (CKD), also known as chronic renal disease, is characterized by slow progressive loss of kidney function. Unlike acute kidney disease which may be reversible, CKD irreversibly progresses through five stages (Stages 1-5) of deteriorating kidney function. Stage 1 is slightly diminished kidney function. Gradual, permanent destruction of kidney tissue eventually leads to Stage 5 CKD, also called end-stage renal disease (ESRD), chronic kidney failure (CKF) or chronic renal failure (CRF), which requires kidney replacement therapies such as dialysis or transplantation, and ultimately leads to death.
CKD is a major worldwide public health problem. According to the National Kidney Foundation, 20 million Americans, or one in nine adults in the U.S., have CKD and another 20 million more are at increased risk of developing CKD. In the U.S., there is a rising incidence and prevalence of kidney failure. The number of patients enrolled in the ESRD Medicare-funded program has increased from approximately 10,000 beneficiaries in 1973 to 472,099 as of 2004. While recent trends show that the rate of increase of new cases has progressively flattened, the projected number of ESRD patients by the year 2010 has been estimated to be 651,330. Early detection of CKD is critical in order to prevent or delay progression of CKD, and to provide proper treatment to CKD patients.